Antimicrobial efficacy of platinum-doped silver nanoparticles

Silver nanoparticles (AgNPs) have been proposed to combat oral infection due to their efficient ionic silver (Ag⁺ ) release. However, concentrations required for antimicrobial efficacy may not be therapeutically viable. In this work, platinum-doped silver nanoparticles (Pt-AgNPs) were explored to evaluate their potential for enhanced Ag⁺ release, which could lead to enhanced antimicrobial efficacy against S. aureus, P. aeruginosa, and E. coli. AgNPs doped with 0.5, 1, and 2 mol% platinum (Pt_0.5 -AgNPs, Pt₁ -AgNPs, and Pt₂ -AgNPs) were synthesized by a chemical reduction method. Transmission electron microscopy revealed mixed morphologies of spherical, oval, and ribbon-like nanostructures. Surface-enhanced Raman scattering revealed that the surface of Pt-AgNPs was covered with up to 93% Pt. The amount of Ag⁺ released increased 16.3-fold for Pt₂ -AgNPs, compared to AgNPs. The initial lag phase in bacterial growth curve was prolonged for Pt-AgNPs. This is consistent with a Ag⁺ release profile that exhibited an initial burst followed by sustained release. Doping AgNPs with platinum significantly increased the antimicrobial efficacy against all species. Pt₂ -AgNPs exhibited the lowest minimum inhibitory concentrations, followed by Pt₁ -AgNPs, Pt_0.5 -AgNPs, and AgNPs, respectively. Doping AgNPs with a small amount of platinum promoted the release of Ag⁺ , based on the sacrificial anodic effect, and subsequently enhanced their antimicrobial efficacy.